(Object) To provide a micro-bubble generator capable of efficiently generating bubbles having a particle size of a nanometer order. (Solution Means) A micro-bubbles generator (1) having a gas-liquid swirl chamber (3), a fluid introduction opening (4) connected to the swirl chamber, the fluid introduction opening for introducing a fluid along a line tangent to an inner surface of the swirl chamber, and a gas-liquid discharge tube (9) for guiding the fluid in the direction substantially perpendicular to the direction in which the fluid is introduced, wherein the discharge tube penetrates a second wall surface (7) of the swirl chamber and protrudes to an interior of the swirl chamber, the micro-bubble generator for applying swirl force to the gas-liquid mixture fluid in the gas-liquid swirl chamber and reducing the size of bubbles by shear force.
